Sit with some object. Look intensely at it. Let your whole mind be completely filled with the memory of that object. If you are sitting with somebody’s photograph, let your whole mind be filled with the memory of that person, your experiences with that person. Let the experiences fill your inner space.
Now close your eyes, withdrawing your sight from the object. Sit inside the inner space, with the same thoughts, and see the object or person in the inner space for a few minutes.
First, see the object or person in the outer space and the inner space. Then see them only in the inner space. Then drop that also and just remain with your being. Decide consciously to withdraw even your thoughts and just be.
source: Living Enlightenment